This non-provisional application claims priority under 35 U.S.C. xc2xa7 119(a) on patent application No, 72907/2000 filed in Korea on Dec. 4, 2000, which is herein incorporated by reference.
The present invention relates to a vacuum circuit breaker which is one of industrial electric devices used between submission and distribution of electricity on an industrial electric cable, and particularly, to a vacuum circuit breaker which is able to be installed in a narrow electrical power distributing cabinet by disposing a switching mechanism unit and an actuator unit in a lengthwise direction, and at the same time, the power of the actuator unit can be transmitted to a plurality of switching mechanism units evenly.
Generally, a breaker is a electric protective device which protects electric load devices and an electric power cable from a large accident current caused by an electrical shortage and a ground fault which may be generated on an electric circuit, and it performs a breaking operation automatically when such an accident current is generated, whereby the circuit is broken.
The vacuum circuit breaker is one of the breaker by which the circuit can be broken rapidly by extinguishing an arc in a vacuum chamber when the circuit is opened/closed and when the circuit is broken by a generation of the accident current.
Herein, a vacuum circuit breaker according to the prior art will be described as follows with reference to FIGS. 1, 2, and 3.
FIG. 1 is a front view showing the vacuum circuit breaker according to the prior art, FIG. 2 is a side view showing the vacuum circuit breaker according to the prior art, and FIG. 3 is a side cross sectional view showing an inner structure of the vacuum circuit breaker according to the prior art.
As shown in FIGS. 1 and 2, the vacuum circuit breaker according to the prior art comprises: three switching mechanism units 20 having stationary contacts and movable contacts respectively and corresponding to three-phases alternating current so as to make a main current to flow when normal state and to break the circuit when Ma large accident current is generated; an actuator unit 10 for providing the movable contact with dynamic power so that the circuit between the two contacts of the switching mechanism units 20 is opened/closed; and a supporting and transfer unit 30 for supporting the switching mechanism units 20 and the actuator unit 10, and including transfer mechanisms for transferring the dynamic power from the actuator unit 10 to the switching mechanism units 20 to connect or break the circuit.
In the vacuum circuit breaker described above, the actuator unit 10 is located on front position in Figure, and the three switching mechanism units 10 are disposed on rear position of the actuator unit 10 in widthwise direction for the actuator unit 10. And a supporting and transfer unit 30 is connected to lower parts of the actuator unit 10 and the switching mechanism unit 20,
The inner structure of the vacuum circuit breaker according to the prior art will be described with reference to FIG. 3. The inside of the vacuum circuit breaker comprises: a rotary shaft 31 which is rotated in order to transfer the dynamic power generated in the actuator unit 10 to the respective switching mechanism units 20; a lever 32 connected to the rotary shaft 31 so as to be rotated with the rotary shaft 31; a roller 33 coupled to an end of the lever 32 so as to be rotatable; a guide 37 coupled to the lever 32 and including an aperture 37a which provides a space in which the roller 33 is able to move in length direction; spring seats 36 and 36xe2x80x2 installed on a outer circumference of the guide 37; a compressive spring 35 for providing the roller 33 with an elastic force by being supported by the spring seats 36 and 36xe2x80x2; a transfer lever 38 having one end connected lower end part of the guide 37 and the other end connected to the switching mechanism unit 20 for transmitting the dynamic power from the actuator unit 10 to the switching mechanisms unit 20 while rotating to clockwise direction or to counter-clockwise direction.
In more detail, an insulating rod 21 is coupled to the other end of the transfer lever 38 in vertical direction, and a movable contact 23 which is able to move to a position which contacts to the stationary contact 25 or to a position which is separated from the stationary contact 25 while vertically moving is disposed on upper end part of the insulating rod 21.
Herein, three levers 32, three rollers 33, three guides 37, three compressive springs 35, and three transfer levers 38 are disposed in the actuator unit 10 and in the supporting and transfer unit 30 so as to transmit the dynamic power to the three respective switching mechanism units 20, and the insulating rod 21, the stationary contact 25, and the movable contact 23 are disposed in the three switching mechanism units 20.
The operation of the vacuum circuit breaker of the prior art will be described as follows.
When the actuator unit 10 rotates the rotary shaft 31 and the lever 32 to the clockwise direction so that a circuit between the two contacts 23 and 25 of the switching mechanism unit 20 is closed, the roller 33 compresses the compressive spring 35 and rotates the transfer lever 38 to the counter clockwise direction.
At that time, the insulating rod 21 goes up by the rotation of the transfer lever 38 to the counter clockwise direction, and then the movable contact 23 contacts to the stationary contact 25, so the electrical circuit between the three phases alternative electric source and the electrical load devices is closed.
Also, if the rotary shaft 31 is further rotated to the clockwise direction after the movable contact 23 contacts to the stationary contact 25, then the spring seat 36xe2x80x2 abutted to the roller 33 is moved to lower position along with the outer circumference of the guide 35 and compresses the compressive spring 35, the elastically energized spring 35 pushes up the insulating rode 21 of the switching mechanist unit 20 via transfer lever 38, and then the contact between the two contacts 23 and 25 is maintained, whereby the turn-on operation of the vacuum circuit breaker is completed.
On the other hand, if the rotary shaft 31 and the lever 32 are rotated to counter clockwise direction, the roller 33 releases the compressed spring 35 and the transfer lever 38 is rotated to clockwise direction.
At that time, the insulating rod 21 is lowered by the rotation of the transfer lever 38, and the movable contact 23 is separated from the stationary contact 25 then the circuit between the three phases alternative electric source and the electrical load devices is opened. Therefore, the circuit breaking operation of the vacuum circuit breaker is completed.
However, according to the conventional vacuum circuit breaker described above, the actuator unit 20 is located on front position and the three switching mechanism units 20 are located in widthwise direction. Therefore, if the vacuum circuit breaker is installed on rear inside portion of a electrical power distributing cabinet (not shown) which has complex and limited installation space, it is difficult to ensure the installation space inside the power distributing cabinet, and to maintain and repair the vacuum circuit breaker because the space in the power distributing cabinet is limited.
Also, according to the vacuum circuit breaker of the prior art, the power transmitting mechanisms such as the transfer lever 38 for transmitting the dynamic power from the actuator unit 10 to the switching mechanism units 20 are respectively disposed on the three switching mechanism units 20, and therefore the entire number of components is increased and the structure of the apparatus becomes complex. In addition, if the transmitting speed of the power transmitted through the respective transfer levers 38 are different from each other, the opening/closing operations performed by the respective switching mechanism units 20 are not made at the same time, whereby the reliability of the vacuum circuit breaker is reduced.
Therefore, an object of the present invention is to provide a vacuum circuit breaker in which an actuator unit arid a plurality of switching mechanism units are successively disposed in lengthwise direction, whereby the vacuum circuit breaker is able to be installed inside a power distributing cabinet easily and a maintenance can be performed effectively.
Also, another object of the present invention is to provide a vacuum circuit breaker in which a dynamic power from the actuator unit is able to be distributed evenly to the plurality of switching mechanism units using a common link device, and therefore opening/closing operations of the respective switching mechanism units are performed at the same time and the operation reliability of the vacuum circuit breaker is increased.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a vacuum circuit breaker comprising: a plurality of switching mechanism units having a movable contact and a stationary contact for connecting/breaking an electrical circuit between an electric source and an electric load and disposed in lengthwise direction; an actuator unit including at least one rotary shaft for providing the movable contact with a dynamic power in order to move the movable contact to a position which contacts to the stationary contact or to a position which is separated from the stationary contact; a supporting frame for fixing and supporting the switching mechanism units and the actuator unit; a transfer link means including a transfer link unit, which is coupled to the rotary shaft for transferring the rotating movement of the rotary shaft to horizontally straight movement, for transferring rotating movements of the rotary shaft to a plurality of vertical movements; and a plurality of rotating links having one end pert coupled to the transfer link means and the other end part coupled to the switching mechanism units for transferring the horizontal rotating movement of the transfer link means to vertical movement for position switching of the movable contact.
The foregoing and other objects, featured, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.